Ultrasonic bonding apparatus and methods

Abstract

This invention pertains to apparatus and methods for intermittently creating ultrasonic bonds in sequentially advancing work piece segments, in a nip. The work piece segments are up to about 0.25 inch thick. The apparatus comprises a frame, anvil support apparatus supporting an anvil, and horn support apparatus supporting an ultrasonic horn. The ultrasonic horn and anvil are collectively mounted and configured such that the ultrasonic horn and anvil can be brought together to define the nip. The frame, anvil support apparatus, and horn support apparatus collectively are sufficiently rigid that the horn and anvil can be brought together with interference levels of about 0.000 to about 0.008 inch at a raised bonding portion in combination with defining sufficient nip pressure to develop ultrasonic bonds in work piece segments passing through the nip. The method comprehends bringing a back-up roll, mounted above the ultrasonic horn, into engagement with the ultrasonic horn, to directly support the horn. First and second support rolls can be used to releasably support opposing sides of the outer surface of the ultrasonic horn, preferably below the axis of the horn, whereby the support rolls can be used to lift the horn into engagement with the back-up roll.

Having thus described the invention, what is claimed is:  
     
       1. Ultrasonic bonding apparatus for intermittently creating ultrasonic bonds in sequentially advancing work piece segments, in a nip, wherein the work piece segments to be bonded are up to about 0.25 inch thick, said ultrasonic bonding apparatus comprising: 
       (a) a frame;  
       (b) anvil support apparatus defining an anvil loading assembly connected to said frame, and supporting an anvil roll mounted for rotation about a first generally horizontal axis, said anvil roll comprising a first relatively smaller radius portion extending about a first portion of a circumference of said anvil roll, and at least one raised bonding portion having a second relatively larger radius extending about a second portion of the circumference of said anvil roll; and  
       (c) horn support apparatus connected to said frame, and supporting a rotary ultrasonic horn mounted for rotation about a second generally horizontal axis, aligned with the first generally horizontal axis.  
       said ultrasonic horn and said anvil roll collectively being mounted and configured such that said ultrasonic horn and said anvil roll can be brought together to define a nip therebetween, and wherein said anvil roll and said ultrasonic horn can rotate in common with movement of work piece elements through the nip, and intermittent passage of said raised bonding portion through the nip, 
       said frame, said anvil support apparatus, and said horn support apparatus collectively being sufficiently rigid that said horn and said anvil roll can be brought together with interference levels of from about 0.000 inch to about 0.008 inch at the raised bonding portion in combination with defining sufficient nip pressure to develop ultrasonic bonds in the work piece segments passing through the nip. 
     
     
       2. Ultrasonic bonding apparatus as in  claim 1 , a width being defined between the ultrasonic horn and the anvil roll, said anvil support apparatus including a resilient support member defining a resistance, to withdrawal of the anvil roll from the nip, of about 400 pounds per inch width of the nip. 
     
     
       3. Ultrasonic bonding apparatus as in  claim 1 , said anvil support apparatus further comprising a lifting plate for lifting and lowering said anvil loading assembly with respect to said ultrasonic horn. 
     
     
       4. Ultrasonic bonding apparatus as in  claim 1 , said anvil support apparatus further comprising a pivot plate pivoting the anvil loading assembly about a third axis oriented perpendicular to the first axis. 
     
     
       5. Ultrasonic bonding apparatus as in  claim 1 , including a stop defining a limit to downward travel of said anvil loading assembly. 
     
     
       6. Ultrasonic bonding apparatus as in  claim 1 , including a back-up roll mounted above said ultrasonic horn, and wherein said back-up roll engages an outer surface of said ultrasonic horn in alignment with the first and second axes. 
     
     
       7. Ultrasonic bonding apparatus as in  claim 6 , including an adjusting screw, operating on a cradle arm, for adjusting a height of said back-up roll, and thus generally defining an upper limit to movement of said ultrasonic horn. 
     
     
       8. Ultrasonic bonding apparatus as in  claim 1 , including first and second support rolls releasably supporting opposing sides of an outer surface of said ultrasonic horn. 
     
     
       9. Ultrasonic bonding apparatus as in  claim 8  wherein axes of said first and second support rolls are positioned lower than the axis of the ultrasonic horn, whereby urging said first and second support rolls inwardly against the outer surface of said ultrasonic horn lifts said ultrasonic horn upwardly against said back-up roll. 
     
     
       10. Ultrasonic bonding apparatus as in  claim 8 , said first and second support rolls being mounted to a horn support plate through an activation assembly, said horn support apparatus further comprising equalizer arms mounted to said horn support plate, and equalizing inward and outward movement of the first and second support rolls. 
     
     
       11. Ultrasonic bonding apparatus as in  claim 1  wherein the second radius is about 0.01 inch to about 0.25 inch greater than the first radius. 
     
     
       12. A method of intermittently creating ultrasonic bonds in sequentially advancing work piece segments, wherein the work piece segments to be bonded are up to about 0.25 inch thick, the method comprising: 
       (a) passing the work piece segments through a nip defined by a frame, anvil support apparatus defining an anvil loading assembly connected to the frame and supporting an anvil roll mounted for rotation about a first generally horizontal axis, the anvil roll comprising a first relatively smaller radius portion extending about a first portion of a circumference of the anvil roll and at least one raised bonding portion having a second relatively larger radius extending about a second portion of the circumference of the anvil roll, and horn support apparatus connected to the frame, and supporting a rotary ultrasonic horn mounted for rotation about a second generally horizontal axis, aligned with the first generally horizontal axis;  
       (b) bringing the ultrasonic horn and the anvil roll together in defining the nip with interference of about 0.000 inch to about 0.008 inch at the raised bonding portion, and correspondingly developing suitable pressure in the nip to create ultrasonic bonds;  
       (c) activating ultrasonic energy in the ultrasonic bonding horn; and  
       (d) rotating the ultrasonic horn and anvil roll in common with movement of the work piece segments through the nip, and thereby intermittently applying pressure to the work piece segments at the raised bonding portion, and creating ultrasonic bonds in the work piece segments passing through the nip.  
     
     
       13. A method as in  claim 12 , including applying first and second support rolls to sides of the ultrasonic horn and lifting the ultrasonic horn into engagement with a back-up roll aligned with the first and second axes such that the first and second support rolls, in combination with the back-up roll, define a fixed location of the ultrasonic horn. 
     
     
       14. A method as in  claim 13 , including applying the first and second support rolls to the sides of the ultrasonic horn at locations lower than the second axis, and urging the first and second support rolls against the ultrasonic horn and thereby lifting the ultrasonic horn into engaging relationship with the back-up roll. 
     
     
       15. A method as in  claim 13 , including prior to lifting the ultrasonic horn into engagement with the back-up roll, moving the back-up roll to the sag distance of the ultrasonic horn such that upon the horn being lifted into engagement with the back-up roll, substantially all sag is removed from the ultrasonic horn. 
     
     
       16. A method as in  claim 14 , including prior to lifting the ultrasonic horn into engagement with the back-up roll, moving the back-up roll to the sag distance of the ultrasonic horn such that upon the horn being lifted into engagement with the back-up roll, substantially all sag is removed from the ultrasonic horn. 
     
     
       17. A method as in  claim 12  wherein the bringing of the anvil roll and the ultrasonic horn together primarily comprises lifting the anvil roll, thereby to bring the anvil roll into engaging relationship with an outer surface of said ultrasonic horn. 
     
     
       18. A method as in  claim 12 , including pivoting the anvil roll about an axis perpendicular to the first axis thereby to bring the first axis into alignment with the second axis. 
     
     
       19. A method as in  claim 12 , including limiting downward movement of the anvil loading assembly and thereby preventing disengagement of drive gears which transmit drive power between the anvil support apparatus and the horn support apparatus. 
     
     
       20. A method as in  claim 13 , including adjusting height of the back-up roll and thereby controlling height of the ultrasonic horn. 
     
     
       21. A method as in  claim 13 , including releasing the support rolls and the backup roll from engagement with the ultrasonic horn, and re-engaging the support rolls and back-up roll with the ultrasonic horn, and thereby returning the ultrasonic horn to the defined location. 
     
     
       22. A method as in  claim 14 , including releasing the support rolls and back-up roll from engagement with the ultrasonic horn, and re-engaging the support rolls and back-up roll with the ultrasonic horn, and thereby returning the ultrasonic horn to the defined location. 
     
     
       23. A method of intermittently creating ultrasonic bonds in sequentially advancing work piece segments, wherein the work piece segments to be bonded are up to about 0.25 inch thick, the method comprising: 
       (a) passing the work piece segments through a nip defined by a frame, anvil support apparatus defining an anvil loading assembly connected to the frame and supporting an anvil roll mounted for rotation about a first generally horizontal axis, the anvil roll comprising a first relatively smaller radius portion extending about a first portion of a circumference of the anvil roll and at least one raised bonding portion having a second relatively larger radius extending about a second portion of the circumference of the anvil roll, and horn support apparatus connected to the frame, and supporting a rotary ultrasonic horn mounted for rotation about a second generally horizontal axis, aligned with the first generally horizontal axis;  
       (b) bringing the horn, mounted below a back-up roll, into engagement with the back-up roll;  
       (c) bringing the anvil roll into contact with the ultrasonic horn thereby defining the nip, and correspondingly developing suitable pressure in the nip to create ultrasonic bonds;  
       (d) activating ultrasonic energy in the ultrasonic bonding horn; and  
       (e) rotating the ultrasonic horn and anvil roll in common with movement of the work piece segments through the nip, and thereby intermittently applying pressure to the work piece segments at the raised bonding portion, and creating ultrasonic bonds in the work piece segments passing through the nip.  
     
     
       24. A method as in  claim 23 , including applying first and second support rolls to sides of the ultrasonic horn and lifting the ultrasonic horn into engagement with the back-up roll such that the back-up roll is aligned with the first and second axes such that the first and second support rolls, in combination with the back-up roll, define a fixed location of the ultrasonic horn. 
     
     
       25. A method as in  claim 24 , including applying the first and second support rolls to the sides of the ultrasonic horn at locations lower than the second axis, and urging the first and second support rolls against the ultrasonic horn and thereby lifting the ultrasonic horn into engaging relationship with the back-up roll. 
     
     
       26. A method as in  claim 25 , including prior to lifting the ultrasonic horn into engagement with the back-up roll, moving the back-up roll to the sag distance of the ultrasonic horn such that upon the horn being lifted into engagement with the back-up roll, substantially all sag is removed from the ultrasonic horn. 
     
     
       27. A method as in  claim 23  wherein the bringing of the anvil roll and ultrasonic horn together primarily comprises lifting the anvil roll, thereby to bring the anvil roll into engaging relationship with an outer surface of the ultrasonic horn. 
     
     
       28. A method as in  claim 23 , including pivoting the anvil roll about an axis perpendicular to the first axis thereby to bring the first axis into alignment with the second axis. 
     
     
       29. A method as in  claim 23 , including limiting downward movement of the anvil loading assembly and thereby preventing disengagement of drive gears which transmit drive power between the anvil support apparatus and the horn support apparatus. 
     
     
       30. A method as in  claim 23 , including adjusting height of the back-up roll and thereby controlling height of the ultrasonic horn. 
     
     
       31. A method as in  claim 24 , including releasing the support rolls and the back-up roll from engagement with the ultrasonic horn, and re-engaging the support rolls and back-up roll with the ultrasonic horn, and thereby returning the ultrasonic horn to the defined location. 
     
     
       32. A method as in  claim 25 , including releasing the support rolls and back-up roll from engagement with the ultrasonic horn, and re-engaging the support rolls and back-up roll with the ultrasonic horn, and thereby returning the ultrasonic horn to the defined location. 
     
     
       33. Ultrasonic bonding apparatus for intermittently creating ultrasonic bonds in sequentially advancing work piece segments, in a nip, wherein the work piece segments to be bonded are up to about 0.25 inch thick, said ultrasonic bonding apparatus comprising: 
       (a) a frame;  
       (b) anvil support apparatus defining an anvil loading assembly connected to said frame, and supporting an anvil roll mounted for rotation about a first generally horizontal axis, said anvil roll comprising a first relatively smaller radius portion extending about a first portion of a circumference of said anvil roll, and at least one raised bonding portion having a second relatively larger radius extending about a second portion of the circumference of said anvil roll; and  
       (c) horn support apparatus connected to said frame, and supporting a rotary ultrasonic horn mounted for rotation about a second generally horizontal axis, aligned with the first generally horizontal axis,  
       said ultrasonic horn and said anvil roll collectively being mounted and configured such that said ultrasonic horn and said anvil roll can be brought together to define a nip therebetween, and wherein said anvil roll and said ultrasonic horn can rotate in common with movement of work piece elements through the nip, and intermittent passage of said raised bonding portion through the nip, 
       said horn support apparatus being adapted to fix the position of said horn with respect to said frame during bonding operation such that cantilever elements of force vectors are canceled by opposing force vectors, whereby cantilever vectors have little or no effect on positioning of said horn. 
     
     
       34. Ultrasonic bonding apparatus as in  claim 33 , including a back-up roll mounted above said ultrasonic horn, and wherein said back-up roll engages an outer surface of said ultrasonic horn in alignment with the first and second axes. 
     
     
       35. Ultrasonic bonding apparatus as in  claim 34 , including-an adjusting screw, operating on a cradle arm, for adjusting a height of said back-up roll, and thus generally defining an upper limit to movement of said ultrasonic horn. 
     
     
       36. Ultrasonic bonding apparatus as in  claim 33 , including first and second support rolls releasably supporting opposing sides of an outer surface of said ultrasonic horn. 
     
     
       37. Ultrasonic bonding apparatus as in  claim 36  wherein axes of said first and second support rolls are positioned lower than the axis of the ultrasonic horn, whereby urging said first and second support rolls inwardly against the outer surface of said ultrasonic horn lifts said ultrasonic horn upwardly against said back-up roll. 
     
     
       38. Ultrasonic bonding apparatus as in  claim 36 , said first and second support rolls being mounted to a horn support plate through an activation assembly, said horn support apparatus further comprising equalizer arms mounted to said horn support plate, and equalizing inward and outward movement of the first and second support rolls. 
     
     
       39. A method of intermittently creating ultrasonic bonds in sequentially advancing work piece segments, wherein the work piece segments to be bonded are up to about 0.25 inch thick, the method comprising: 
       (a) passing the work piece segments through a nip defined by  
       (i) a frame,  
       (ii) anvil support apparatus defining an anvil loading assembly connected to the frame and supporting an anvil roll mounted for rotation about a first generally horizontal axis, the anvil roll comprising a first relatively smaller radius portion extending about a first portion of a circumference of the anvil roll and at least one raised bonding portion having a second relatively larger radius extending about a second portion of the circumference of the anvil roll, and  
       (iii) horn support apparatus connected to the frame, and supporting a rotary ultrasonic horn mounted for rotation about a second generally horizontal axis, aligned with the first generally horizontal axis;  
       (b) bringing the anvil roll into contact with the ultrasonic horn, and fixing the position of the horn with respect to the frame such that cantilever elements of force are canceled by opposing force vectors, whereby cantilever vectors have little or no effect on positioning of the horn, the bringing of the anvil roll into contact with the ultrasonic horn and the fixing of the position of the horn defining the nip and developing suitable pressure in the nip to create ultrasonic bonds;  
       (c) activating ultrasonic energy in the ultrasonic bonding horn; and  
       (d) rotating the ultrasonic horn and anvil roll in common with movement of the work piece segments through the nip, and thereby intermittently applying pressure to the work piece segments at the raised bonding portion, and creating ultrasonic bonds in the work piece segments passing through the nip.  
     
     
       40. A method as in  claim 39 , including applying first and second support rolls to sides of the ultrasonic horn and lifting the ultrasonic horn into engagement with the back-up roll such that the back-up roll is aligned with the first and second axes such that the first and second support rolls, in combination with the back-up roll, define a fixed location of the ultrasonic horn. 
     
     
       41. A method as in  claim 40 , including applying the first and second support rolls to the sides of the ultrasonic horn at locations lower than the second axis, and urging the first and second support rolls against the ultrasonic horn and thereby lifting the ultrasonic horn into engaging relationship with the back-up roll. 
     
     
       42. A method as in  claim 41 , including prior to lifting the ultrasonic horn into engagement with the back-up roll, moving the-back-up roll to the sag distance of the ultrasonic horn such that upon the horn being lifted into engagement with the back-up roll, substantially all sag is removed from the ultrasonic horn. 
     
     
       43. A method as in  claim 39  wherein the bringing of the anvil roll and ultrasonic horn together primarily comprises lifting the anvil roll, thereby to bring the anvil roll into engaging relationship with an outer surface of the ultrasonic horn. 
     
     
       44. A method as in  claim 39 , including pivoting the anvil roll about an axis perpendicular to the first axis thereby to bring the first axis into alignment with the second axis. 
     
     
       45. A method as in  claim 39 , including adjusting height of the back-up roll and thereby controlling height of the ultrasonic horn. 
     
     
       46. A method as in  claim 41 , including releasing the support rolls and back-up roll from engagement with the ultrasonic horn, and re-engaging the support back-up roll with the ultrasonic horn, and thereby returning the ultrasonic horn to the defined location. 
     
     
       47. A method of creating ultrasonic bonds in sequentially advancing absorbent article substrate work piece segments, wherein the work piece segments to be bonded are up to about 0.25 inch thick, the method comprising: 
       (a) passing the work piece segments through a nip defined by an anvil roll mounted for rotation about a first axis, the anvil roll comprising a width and a circumference, said anvil roll further comprising a first relatively smaller radius portion extending about a first portion of a circumference of the anvil roll and at least one raised bonding element having a second relatively larger radius extending about a second portion of the circumference of the anvil roll, and a rotary ultrasonic horn mounted for rotation about a second axis, aligned with the first axis;  
       (b) bringing an ultrasonic horn and the anvil roll together in defining the nip with interference of about 0.000 inch to about 0.008 inch at the raised bonding element, and correspondingly developing suitable pressure in the nip to create ultrasonic bonds;  
       (c) activating ultrasonic energy in the ultrasonic bonding horn; and  
       (d) rotating the ultrasonic horn and anvil roll in common with movement of the work piece segments through the nip, and thereby intermittently applying pressure to the work piece segments at the raised bonding element, and creating ultrasonic bonds in the work piece segments passing through the nip.  
     
     
       48. A method as in  claim 47  wherein said raised bonding element further comprises an operating surface represented by an area defined by the width of said raised bonding element and the second portion of the circumference of said anvil roll. 
     
     
       49. A method as in  claim 48  wherein said anvil roll comprises a transition gradient between said first portion of the circumference of said anvil roll and said raised bonding element, product of said transition gradient and width of said raised bonding element defining a loading surface of said transition gradient. 
     
     
       50. A method as in  claim 49  wherein said operating surface of said raised bonding element of said anvil roll comprises an array of bonding projections thereon extending around said respective second portion of the circumference of said anvil roll, and across the entirety of the transverse width of said raised bonding element, thereby covering substantially the entirety of said operating surface of said raised bonding element of said anvil roll. 
     
     
       51. A method as in  claim 49  wherein said operating surface of said raised bonding element of said anvil roll comprises an array of bonding projections thereon, said projections being disposed in discrete spaced arrays which cover portions but not all of either or both of the circumference or width of said operating surface of said raised bonding element of said anvil roll. 
     
     
       52. A method as in  claim 47  wherein said raised bonding element of said anvil roll, including a first larger radius portion of the anvil roll, provides bonding activity at thinner sections of a web of material, and said second relatively smaller radius portion of said anvil roll provides clearance between the anvil roll and said horn for passage of relatively thicker sections of said web between said anvil roll and said horn. 
     
     
       53. A method as in  claim 47  wherein, when said raised bonding element of said anvil roll passes into and through said nip, the presence of said raised bonding element in combination with interference between said raised bonding element of said anvil roll, and said horn, imposes stress on both said horn and said anvil roll, thus providing suitable force at said nip to develop ultrasonic bonds using ultrasonic energy being expressed by said horn. 
     
     
       54. A method as in  claim 47  wherein, when the raised bonding element of the anvil roll is not disposed in the nip, and the smaller radius portion of the anvil roll is disposed in the nip, the nip force is substantially less than the force required to form ultrasonic bonds.